Method for centrifugal amalgamation and precipitation of gold and silver



Jan. 22 1924. 1,481,311

w. H. APPLETON METHOD FOR CENTRIFUGAL AMALGAMATION AND PRECIPITATION vOF GOLD AND SILVER Original Filed April 28. 1919 2 Sheets-Sheet 1 70226 67 lake/5 Zibdz'cczte farae ca rzatarzZQ deeZz'zqy BY rarazrzqy Caz/soda. 2 MW 1111. 22 ,1121. v 1,111,111 W. H. APPLETON METHOD FOR CENTRIFUGAL AMALGAMATION AND PRECIPITATION OF GOLD AND SILVER Original Filed April 28 1919 2 Sheets-Sheet Z INVENTOR J'VzZerXWZZzz MZT SRNEY Patented Jan. 22, 1 924. I I.

- untrue TA-res 1,481,311 PATENT OFFICE,

wmsua n. Arrnnron, or SPOKANE, wasnm'eron, ASSIGNOR 'ro wiasrmm METALS company, or sroxann, WASHINGTON, A conrommon or wasnme'ro'n.

mn'rnon roa cnu'rmrueaz, mercenaries AND rnncxrim'rron or com) AND ,srnvna.

Application fileaa m 28,1919, Serial No. 293,362. Renewed December 17; 1923.

. To all whom it may concernif v, Be itknown that I, VILBUR H.'-APPLET0N, a citizen of the United States, residing at- Spokane, in the county of Spokane and 5 State of \Vashington, have invented new and.

useful Improvements in Methods-for Centrifugal" Amalgamation and Precipitation of Gold and Silver, of which the following is acspecificatipn. Y a

This invention relates to an improved method and means' for the centrifugal amalgamation of the nobler meta-ls by mercury. I

()ne of the most important features and utilities relates to the conversion, electrolytically, of dissolved values from a solutioh ti) suspension in liquid, the particles of such suspension being discharged onto the mercury, and acted upon bycentrifugal forcetodrive the values, in suspension, into which the values are amalmercury, and as the bowlrotates, imparting revolvable movement to the mercury therein, the latter having its cathodal surface infinitely multiplied and thereby very greatly increasing the rate of precipitation with re'-- spect to the mercurial area presented, j

A further very important feature consists to in :the simultaneous amalgamation ofv both the free oruncoatedfv'alues present in the pulp, by the sole medium; of centrifugal actiomf'and the-dissolved values converted {electrolytically solution into suspenat sion which latter acted upon to drive L -tl 1em; into-the-mercury not only by ,the centrifugal forceto which they'are subjected, but'-,-. jalso' by" the cations which radiate through the electrolyte toward and seek the mercurial'cathode. v It isai feature ofmy invention to centrifuga lly spread the mercury over its supporting surface in the bowl not only in uni form thickness but in such ainanner as to retain the mercury inthe form of body. Thus-it is a gregatdesideratfum of my invention to preventgttheimer'cury from fiouring. It is-alsog. =afeaturelof this invention to spreadithe'mercury. in as thin a body f-tieles on the mercury, will both :,not only thinly by "centrifugal action, but

with a thinness which is uniform throughas possible,-.over its supporting surface,'.as it is well known that'merely a covering of the surface is sufficient for the purposes of amalgamation and anything" further is mere waste. In order to promote the greatest efliciency and speed of amalgamation,- it is a feature of-my invention to prepare the pulp solution sufliciently liquid,-and to feed it insiich proportion in volume, with relation to the mercurial area, as to prevent the particles 1n suspension from banking ont-he mercury and also to cause the heavler pulp particles, comprising the values, tofilm over the mercurial surface as thinly as possible and thereby bring the values inv suspension into the closest possible proximity to the mercury as the solution flows upwardly along the surface of the latter.

To the end that all the foregoing may be accomplished, it is. a feature of my invention to provide the rotating bowl with a mercury supporting surface which curves upwardly and radially outwardly from near the axis of rotation to the discharge edge, and which surface is continuously smooth and unbroken so that the mercury is free to assume the position to which it may be impelledby centrifugal force. Thus it is a very important feature of my invention to absolutely and entirely free the mercury from any obstruction orimpediment which might. either retard its freedom of move- 'inentor destroyits integrity as a united body. With this in view, it is a feature of my-invention to gradually increase the diameter of the supporting surface toward the dischargirtg edge whereby the mercury may be readily controlled and sustained wholly by the rate of rotation imparted to the bowl, and further; the curvature of the bowl, the quantity {of mercury employed, together with the speed of rotation, are all so correlated, especially in the sense of mutual reciprocation,',that the joint action will result in maintaining gravity and centrifuw gal force in an equilibrium of balance whereby not only the mercury, which does not and will not discharge over the edge of the bowl, but also the heavier ulp par- "out the height of the surface. This correlation of the forces is such that the speed imspread parted to the bowl will not raise the mercury therein to the discharge edge but will raise the solution to and over the discharge edge, only the particles of higher specific gravity being amalgamated;

Other features and objects of my improved mechanism and method will be more fully described in connection with the accompanying drawing and will be more particularly pointed out in and by the appendedclaims.

In .the drawing Figure l is a vertical sectional view of the device of my invention.

Figure 2 is a diagrammatic view illustrative of my theory of the reason why my improved rotary mercurial cathode has a multiplying cathodal surface.

Figur 3,,is view similar to Figure 1, showing the device as it'would appear in actual continuous operation with the heavier particles of the pulp thinly filmed over the mercury and illustrating how the liquid portion of the pulp takes a parabolic curve different from that of the mercury.

Like characters of reference designate similar parts throughout the different figures ofthe drawing.

A bowl is indicated at 1 and the same is provided with a mercury supporting surface 2, the latter, at least, being of an elec-- trically non-conducting material, the surface being a non-amalgamating and noir amalgamated surface. I have used a wood bowl having its surface coated with an asphaltum base. A mounting 3 is provided on which the bowl rests and an axially disposed pipe 4 has an inlet end 5 opening to the bowl through the bottom thereof, the

'pipe extending. through the mounting 3.

Any suitable form of thrust-bearing 6 may be provided, the same being mounted upon a frame 7. The pipe 4, which also functions as a shaft. isjournalled in a second bearing 8 mounted on a lower portion 9 of the frame. The lower open end of the shaft 4 will be suitably provided with a valve controlled outlet (not shown) and a pulley 10 will'be driven by a belt or other suitable means. A spillway has an inner wall 12 which is shown overhung or overlapped by a flange 13 depending from the edge of the bowl. The spill-way is stationary and the outer and inner walls 11 and 12 will be con nected by a bottom wall 14 which is inclined downwardly for delivery to a common outlet 15. A hopper 16.delivers to a discharge pipe 17 which depends into the bowl into contact with the electrolyte. An anode or plus wire 18, of a circuit, is diagrammatically indicated as being connected with pipe 17,,while a cathode or minus wire 19, of said circuit, is diagrammatically indicated in connection with pipe 4. As the mercury 24 extends downwardly in the metallicpipe 4 it will be seen by reference to Figure 3 how the circuit is closed through the mercury from minus wire 19.

Next referring to the novel form of mecface 2 is calculated and developed not necessarily for the production of t the precise curve shown, but for the purpose of presenting such a slope to the mercury 24 that with a givenquantit of the latter and given speed of rotation o the bowl, the mercury 24 will traverse and annularly ascend this slope in such a manner as to be spread over the area thereof in substantially uniform thickness, as shown in Figure 3. The very precipitous incline will resist in a cumulative manner the ascent of the mercury 24 under centrifugal action and thiswill serve to unite rather than segregate or divide the mercury so that as the latter spreads over the surface it will remain united without either the bowl, or the forces acting upon the mercury having any tendency to disintegrate the latter, but on the contrary, pro.- moting unity of the mercury. This will prevent flouring. As will be seen, the mercury supporting surface is parabolic in form. a

The shape of the bowl is designed so that the action of centrifugal force sending the mercury upwardly, will be balanced by the action of gravity tending to cause the mercury to descend. feature of my invention to correlate these forces with the shape of the bowl and the speed of rotation with a view of spreading the mercury evenly over the surface 2.- In large operations it is a matter of economy, and an important one, to use as little mercury as possible in order to get efficient action and so long as the surface is covered, nothing is gained by having a two-inch thickness of mercury at the bottom of the bowl and an eighth of an inch near the top of the bowl. In order to demonstrate the fact that the forces of gravity and centrifugal force are in balance, I have disposed balls of different weight, as indicated at 22 and 23, at different annular elevations on the inner surface 2 and these balls neither seek to ascend or descend, when the bowl is empty. However, fill the bowl or put enough water into ascend to the balls and they will immediately descend. I have also Now it is an important measured the depth of themercurv at different elevations to ness is uniform.

An important feature of the foregoing resides in the fact that wholly by the speed prove that the thickof rotation, the mercury 24 can be prevented from ascending beyond a given elevatlon whereas the liquid portion of the pulp,

while it very slowly traverses its ascent up the mercurial surface, will flow over the edge and carry away the lighter particles. Furthermore, and this is very important, with into the mercury 2-1 because of their near proximity thereto.

This is important not only as regards speed of operation but also etiiciency. v

In straight amalgamation, where the ore is not dissolved in solution, the current is sent through the mercury to prevent. the

' latter from fouling and sickening, which I do not claim as new. All of the foregoing description relates not only tothe importance of the features with respect to-stralg'ht amalgamation wholly by centrifugal action. but also applies to electrical precipitation andcentrifugal amalgamation, the latter, of which features I will nextdescribe in de- 'tail. Q

cerned.

The pulp is ground to the desired fineness in a suitable solution which dissolves some the mercury by straight amalgamation in dependent of any electrolytic action. How-' ever, asregards the metals which are dissolved, it is necessary to convert these into sus ension rior to amal amation. and it'is 'one'of the novel features of this invention am'algamationma'y be simultaneously carried out.

It is'not necessary to recite either the injgredients'of the pulp solution or the electro yte, as far as this invent on is-con- In actual practice ofthe invention, a bowl of the form shown in Fig. 3 with a diameter of 16 90/100 inches :inddepth of 5 96/100 inches has been used, the diameter being measured at the point-21 and the depth being measured from this diameter t the point 20.

With this type of bowlrotating at a constant speed of eighty-three revolutions per minute, forty pounds of mercury will spread over the. surface 2 in a uniform thickness, as,

shown in Figure 3. Of course in practice, the axial outlet is closed at a higher elevation than that shown, as regards the mercury; in pipe 4. As the bowl gradually attams its maximum speed, the mercury will ascend toward dine 21 and will not seek to pass above said definite limit upwardly nor will itd'escend below said'limit when the bowl is rotated at a constant speed, as stated. Of course I do not speak of constant speed as the final ultimate in accuracy, asa variation of one to three revolutions per. minute lnear as 'I can determine, all friction between the mercury and the bowl'ceases. and becomes nil and the mercury rotates bodily at the same speed as the bowl;

- The bowl is first set in motion not only .to spread but to maintain the mercury 24 evenly distributed over the face of thebo'wl, as hereinbefore described. ji The electrolyte 27 and the pulp in solution having been introduced or discharged onto the mercury 24 and the/circuit" having been connected up, the operation will .be, as followsfi; Care will be taken only to admit as mucl f'fas will cause the heavier pulp particles 25'te- .thinly film over the mercury 24, as it isth'e object to not only thinly coat the amalgamatiiig 'surand without interruption. All of those constituents of the pulp' except the nobler metals will be gradually carried over the discharge edge 26 of the bowl by centrifugal action. and the solution 27, as the conveying medium:

the intake being regulated to not exceed or a fall below the rate of discharge thereby pre renting the particles in suspension from banking on the mercury 24. v

The dissolved metals will be converted by action by centrifugal force to be driven into electrolysis into solids and thereby freed for v the mercury 24. The rapidity with which amalgamation can be carried out by my improved method and apparatus has been amply proven in actual practice. To the best of my knowledge and belief, among the reasons why a relatively small amount of mercury 24 in constant revolution will perform the service of many times the quantity of mercury'24 or mercurial surface in astate of quiescence, is that because the cathodal" surface in my improved invention is infi-' ryl revolving, it is my theory that the metal particles in suspension in the mercury 24 meet less resistance in their descent, in the bowl within the mercury 24 than would be the case if these minute particles were interfered with by variantly flowing currents of mercury 24, which latter condition would certainly result, if centrifugal force and gravity were not in a state of balance.

By reason of the supporting surface being continuously smooth, and also because it is not only a non-amalgamated but a-lso'a nonan'ialgamating surface, the mercury 24 is at all points of area exposed to uniform f-riction and therefore I have found that there is no slippage between the mercury 24 and the bowl surface, and that this is one of the. most important reasons why the mercury 24 does not flour.

Because the mercury 24 is held together, as a united body by the very powerful and sustained action of centrifugal force, the pulp does not scour the mercury 24. with consequent loss thereof notwithstanding the fact that rotation of the mercury body and the pulp is notin actual synchronism and that there is relative movement of the two, during joint rotation thereof.

It is also my theory that after the dissolved metals have been transformed into suspension in the electrolyte and before reaching the mercury, their amalgamation is materially assisted, electrolytically by reason of the cations movingtoward and' seeking the cathode. i

'As a method, my invention consists in electrolytically converting metals in solution,

into'suspension, and-,applying not only centrifugal action but also the cations for drivingthevalues in suspension into the mercury 24-, and in this connection, my invent ion,-as a"metl10d, 1ncludes setting the mercury ,cause the mercury 24 to act as the cathode,

and to set the mercury 24in, and maintain it in motion to' multiply the cathodal surface not only to increase the rateof-precipitation but also to greatly reduce {the amount of mercury necessaryf -i'w-" Accord1ng. to"-"my invention, after the mercury 24 has reached its final operative position in the bowl, the mercury revolves in absolute synchronism with the bowl and there is no relative movement between the two.

' I do not wish to be limited to this specific disclosure of my invention, either in apparatus or method, except for such limitations as the claims mayimport.

1. The herein-described method of preventingflouring of mercury for amalgamating. purposes, which consists, in setting a body of mercury in motion at an upward inclination to the horizontal, and in supporting the body of mercury in correlation with application thereto of opposing forces to maintain the mercury united andspread the same in uniform thickness.

2. The herein-described method of centrifugally 'amalgamating the nobler metals with mercury, which consists, in rotating a mercury supporting surface of such upward slope from near the axis of rotation to the discharge edge that centrifugal action will spread the mercury. over such surface, and in feeding pulp onto the mercury in such quantity relation with respect to the speed of rotation and the area of the mercury that the heavier pulp particles will relatively thinly and uniformly film over the mercurial surface.

3. The herein-described method of centrifugal amalgamation of the nobler metals, which consists, in revolving an upwardly inclined non-amalgamating and non-amalgamated mercury supporting surface whereby friction to free movement of the mercury is uniform to prevent fiouring, in coordinating the speed of rotation of said surface in such relation to its inclination as to balance the action of gravity and centrifugal force, whereby the mercury will rotate in substantially fixedrelation with said surface withoutascent or descent or relative rotation therein, whereby the values in amalgamation in the mercury will be free to descend therein without resistance of variant currents of flow of the mercury.

4. The herein-described method of preventing flouring of mercury in centrifugal amalgamation of ore, which consists, in rotating a body of mercury on and with a parabolic supporting surface presenting a cumulative resistance to ascent -of the mercury thereon to prevent flouring, and in speeding up rotation of said surface in such relation to the curvature and size of said surface that the mercury will remain a united body andwill uniformly and thinly film over said surface and will remain substantially quiescent with respect thereto without ascending or descending thereon.

In testimony, that I claim the foregoing as my own, I hereby a-tfix my signature.

VVILBUR H. APPLETON. 

